This invention relates to a sliding window or door construction of the type including an outer frame formed from four elongate elements forming respectively a first post, a second post, a horizontal top rail and a horizontal bottom sill; a fixed panel mounted within the outer frame and a sliding panel mounted in the outer frame for sliding movement from a position adjacent one post against which the sliding panel closes toward the second post to overlap the fixed panel. Devices of this type can be used in a patio door set or as smaller panels in a simple sliding window arrangement.
A number of problems arise with constructions of this type. Firstly the weatherstripping arrangement which is essential to provide sealing between the sliding panel and the outer frame around three sides of the sliding panel and between the sliding panel and the fixed panel along a centre section must receive adequate pressure in the closed position to ensure a proper sealing action while this pressure can interfere with the proper sliding action. Proposals to solve this problem are shown in Canadian Patent 1,078,258 (Allen). In this arrangement the outer frame carries a plurality of wedges against which the sliding panel moves as it approaches the closed position. These wedges action to move the sliding panel transversely to its sliding direction to compress the weatherstripping solely at the closed position while releasing the strong compression when the panel moves away from the closed position. To some extent, therefore, this alleviates the high friction and high wear which are obtained if the sliding panel continually slides against the weatherstripping while under compression. However the design shown is very unsatisfactory and has achieved little commercial success.
Other designs currently available on the marketplace, for example a design manufactured by In-Line Manufacturing Inc. of Toronto, provides highly complex hardware in which an initial action of the door is to move significantly away from contact with the frame and then to slide in the normal sliding direction in the manner of action of an aircraft door or a side sliding door of the type used in many cases on a van. However a design of this type in a sliding door set is less satisfactory in view of the relatively high cost and complexity of the hardware to allow this sliding action.